Collapsible wheelbarrow

ABSTRACT

A heavy duty collapsible wheelbarrow having a frame (including, for example, a wheel and a pair of handles), and a container (sometimes referred to in the prior art as a tray or bucket), the container being securable to the frame in a “ready for use” position, and being releasable from this “ready for use” position to enable the wheelbarrow to be collapsed, the means for securing the container to the frame including an “over-center” mechanism.

This invention relates to wheelbarrows for heavy duty use, for examplein the building trade. Such wheelbarrows may be used for carrying bricksor other building blocks, for carrying concrete or cement, or merely forcarrying rubble.

Wheelbarrows need to be transported to and from building sites at thestart and finish of a job. Also, where a job lasts for more than oneday, if the site is not secure against theft, then it may also benecessary to remove wheelbarrows from the site when work has finishedfor the day and to transport them back to the site for the start of workthe next day. Conventional wheelbarrows have quite long frames measuredfrom handle end to wheel end, and they therefore take up a lot of spaceon a van or other transport.

It may happen that when wheelbarrows need to be transported there isinsufficient space on whatever transport happens to be available at thetime. Of course, a van or other transport can make an additional trip topick up any remaining wheelbarrow(s) that could not be taken on thefirst trip, However, this is clearly unsatisfactory, not only because itis a waste of the drivers time and increases transport costs, but alsobecause it may be necessary to pay a man to guard wheelbarrows awaitingthe return of a driver to pick them up. For the reasons mentioned above,it may be cheaper to abandon one or more wheelbarrows at a building sitethan to return to collect them. It will be apparent from the aboveexplanation that there is a great need for a heavy duty wheelbarrowwhich can be collapsed from a bulky “ready-for-use” position to a spacesaving position in which it can be stowed.

However, in spite of the obvious need for a heavy duty collapsiblewheelbarrow, the inventor has not seen such a wheelbarrow offered forsale,

The only currently available collapsible wheelbarrows known to theinventor are of lightweight construction, and have a collapsiblecontainer portion made of a deformable plastics material, or of canvas.These wheelbarrows are readily convertible between collapsed and “readyfor use” positions, but they are designed for use in the garden, forexample for carrying leaves, grass cuttings or other lightweight items.A wheelbarrow of the construction just described would very soon bedestroyed if used on a building site.

In contrast to the above currently available collapsible wheelbarrows,the present invention is particularly concerned with a heavy dutycollapsible wheelbarrow having a frame (including, for example, a wheeland a pair of handles), and a container (sometimes referred to in theart as a tray or bucket), the container being securable to the frame ina “ready for use” position, and being releasable from this “ready foruse” position to enable the wheelbarrow to be collapsed. One problemwith such wheelbarrows is that of securing the container firmly andrigidly to the frame in such a way that the wheelbarrow can rapidly becollapsed and erected, and it is believed that the reason that heavyduty collapsible wheelbarrows are not available for purchase is thatnobody has yet found a satisfactory solution to this problem.

One could use a number of nuts and bolts. This would be effective in asmuch as it would provide a rigid and secure construction in use, but ithas many disadvantages. For example, nuts and bolts are readily lost;one or more would be needed; care would be needed to ensure that thenuts were securely tightened, and the process would be time consuming.Also, the heads of the bolts, and/or the nuts, would be likely to becomecovered in mud or concrete making access to them difficult. The threadsof the nuts or bolts would also be susceptible to mechanical damage andrust. It is clear from the above that the use of fasteners such as nutsand bolts would be entirely unsatisfactory in a wheelbarrow intended foruse in the building trade.

Instead of nuts or bolts one could use pins adapted to be slid throughholes in the container and through corresponding holes in the frame.This would enable the wheelbarrow to be erected and collapsed muchquicker, but it would have important disadvantages. Firstly, theattachment of the container to the frame would not be as rigid as withnuts and bolts, and, during use of the wheelbarrow, relative movementwould occur in the region where the pins pass through the holes in theframe and in the container. This movement would eventually lead to wearof the pins and of the parts through which they pass. Secondly, the pinswould readily be lost. If the pins were to be hung on chains attached tothe frame to prevent them from being misplaced, the chains would soon bebroken during heavy work in the building trade. Further, it would becomedifficult to remove the pins and to re-insert them as the wheelbarrowbecomes covered in mud, concrete, cement etc.

An aim of one aspect of the present invention therefore is to provide animproved way of securing the container to the frame which overcomes thedisadvantages described above.

According to this aspect of the invention there is provided a heavy dutycollapsible wheelbarrow comprising a frame, a container and means forsecuring the container to the frame in a “ready for use” position, thecontainer being releasable from the “ready for use” position to enablethe wheelbarrow to be collapsed, in which wheelbarrow the means forsecuring the container to the frame includes a fastening mechanism whichis movable between a released position and a locking position and inwhich a tensile or compressive force acting on a member of the mechanismprogressively increases as the fastening mechanism is moved from thereleased position towards the locking position.

In a preferred embodiment the fastening mechanism is an over-centermechanism and the tensile or compression force acting on the memberprogressively increases to a maximum as the mechanism is moved from thereleased position, after which the mechanism snaps to a stable lockingposition.

In another embodiment the tensile or compressive force acting on themember of the fastening mechanism progressively increases up to thelocking position and the mechanism is held in the locking position by acatch.

The fastening mechanism of a preferred wheelbarrow according to theinvention (described in detail below) allows fastening of the containerto the frame to be achieved very quickly indeed, for example in betweenten and thirty seconds depending on how experienced the user is. Thereare no nuts, bolts, or pins which could become lost or damaged, and notools of any kind are required. None of the operative parts of thefastening mechanism lie inside the container to be covered in materialsuch as concrete carried inside the wheelbarrow.

According to another aspect of this invention there is provided a heavyduty collapsible wheelbarrow having a frame, and a container, thecontainer being securable to the frame in a “ready for use” position,and being releasable from this “ready for use” position to enable thewheelbarrow to be collapsed, the frame comprising two parts, one ofwhich carries a wheel for supporting the wheelbarrow on the ground, andthe other of which carries a pair of handles used for lifting andwheeling the wheelbarrow, the two frame parts being either hingedtogether, or being detachably connected together, and both parts of theframe serving in use to support the container.

According to yet another aspect of this invention there is provided aheavy duty collapsible wheelbarrow having a frame and a container, thecontainer being securable to the frame in a “ready for use” position,and being releasable from this “ready for use” position to enable thewheelbarrow to be collapsed, the frame having two crossbars spaced apartin the longitudinal direction of the wheelbarrow so that there is a rearcrossbar and a front crossbar, at least one longitudinal bar beingsecured to the underside of the container, the front crossbarco-operating with the container during assembly of the wheelbarrow todefine a forward end position of the container on the frame, and therear crossbar co-operating with the container for clamping the containerin place on the frame.

According to yet another aspect of this invention there is provided aheavy duty collapsible wheelbarrow having a frame and a container, thecontainer being securable to the frame in a “ready for use” position,and being releasable from this “ready for use” position to enable thewheelbarrow to be collapsed, the mounting of the container on the framebeing achieved in two stages, the first stage involving engaging thecontainer with the frame in such as way that the container cannot belifted from the frame in the region of engagement, although it can stillbe slid out of said engagement, and the second stage involving clampingthe frame and the container together in such a way as to prevent thecontainer being slid out of said engagement with the frame.

In order that the present invention may be more readily understood, onedesign of a collapsible wheelbarrow according to the invention will nowbe described by way of example and with reference to the accompanyingdrawings in which:

FIG. 1 is a perspective view of a frame for a wheelbarrow, the framebeing shown in an unfolded position;

FIG. 2 is a perspective view of a container adapted to be connected tothe frame;

FIG. 3 is a plan view from below showing the frame of FIG. 1 and thecontainer of FIG. 2 assembled together to form a ready-for-usewheelbarrow;

FIG. 4 is a side view of the assembled wheelbarrow of FIG. 3, the frameof the wheelbarrow also being shown in its collapsed configuration bythe dashed outline; and

FIG. 5 is a perspective view showing an “over-center” locking mechanismused in securing the container in place on the frame.

Referring to the above drawings there is shown a collapsible wheelbarrowcomprising a frame 1 and a container 2 (sometimes called a tray orbucket) adapted to be attached to and detached from the frame 1. Theframe itself comprises two parts 3 and 4 connected together at a pair ofhinges 5, best shown in FIG. 4. Frame part 3 comprises the rear or“handle end”, and has a pair of symmetrical sides 6 and 7, each sidebeing made from suitably bent pieces of steel tubing. Each piece of sidetubing 6 and 7 comprises a handle 8 and a conventional generallyU-shaped leg 9 which merges with the handle 8. The handles 8 serve forthe lifting the assembled wheelbarrow so that the legs 9 are clear ofthe ground and wheelbarrow can be wheeled. The legs 9 serve to supportthe wheelbarrow when it is not being wheeled.

A cross bar 10 connects the two sides 6 and 7 together and is welded toboth sides in the regions where the handles 8 merge with the legs 9, Theframe part 4 is the “Wheel end” of the wheelbarrow, and has a pair ofside members 11 formed from a single piece of steel tubing bentgenerally into the shape a letter “V”, a wheel 12 being supported in theapex region of the “V” in conventional manner. A second cross-bar 13connects the side members 11 together in the region generally close tothe hinges 5 at the widest part of the “V”. As best shown in FIG. 1, thecross bar 13 has a portion 13 a which is generally horizontal, and aportion 13 b which extends from the forward edge of the horizontalportion 13 a upwardly and forwardly at an angle of about 40 to 45degrees to the horizontal.

As shown in FIGS. 2. 3, and 4, the container 2 to be secured to theframe 1 is made of steel and it is generally conventional in shape andconstruction, comprising a base 2 a, a pair of side walls 2 b, a rearwall 2 c, and a front wall 2 d. However, in contrast to conventionalwheelbarrows, the container is reinforced by a pair of spaced apartparallel bars 14 and 15 (best shown in FIG. 3) which are secured to thebase 2 a of the container in any suitable way, such as by welding orbolting. These bars 14 and 15 extend generally longitudinally of thewheelbarrow, and as well as providing reinforcement, they also assist insecuring the frame and the container together as will be explainedbelow.

As shown in FIG. 4, there is a space between the underside of the base 2a of the container and the two bars 14 and 15, this space being at itsgreatest size in the region of the forward ends 14 a and 15 a (FIG. 3)of the longitudinal bars. The length of the longitudinal bars 14 and 15on the container is sufficient to span the distance between the twocross bars 10 and 13.

An “over center” mechanism for securing to frame and the containertogether is shown in FIGS. 3 and 5, The mechanism comprises a hook 21mounted on the crossbar 10 of the frame, and a mechanism 22 mounted onthe container 2 to co-operate with the hook 21. The mechanism 22comprises a plate 23 bolted or welded to the rear wall 2 c of thecontainer; an operating lever arm 24 pivoted to the plate 23 at a pivotaxis 25; and a tensioning arm 26.

The plate 23 lies generally parallel with the rear wall 2 c, but has apair of lugs 23 a which are bent at right angles to the wall 2 c , thelugs having holes for the passage of a pivot pin 25 a. The operatinglever arm 24 is pivoted to an end region 24 a to the plate 23, and isarranged to be gripped at an opposite end region 24 b for manualoperation of the lever arm. Arm 24 also has an intermediate region 24 cto which the tensioning arm 26 is pivoted at a pivot axis 26 a. Thetensioning arm 26 is formed from a steel loop which can be said to bevery approximately U-shaped, comprising a pair of side arms 26 a whichare connected together by a base 26 b. The free ends 26 c of the arms 26a of the “U” are bent away from each other to engage holes in theintermediate region of the lever arm 24 to define the pivot axis 26 amentioned above. As shown in FIG. 5, the end 26 b of the tension armengages the hook 21 at an axis 21 a.

The way in which the container (FIG. 2) can be securely mounted on theframe (FIG. 1) will now be described. In a first stage the container 2is lifted from its FIG. 2 position and reversed front to rear to placeit the correct way round relative to the position of the frame 1 in FIG.1. The container 2 is then placed onto the top of the rearmost crossbar10 so that the longitudinal bars 14, 15 rest on top of the crossbar 10.

Next, the container 2 is slid forwardly so that the forward ends 14 aand 15 a of the bars 14 and 15 slide underneath the generally horizontalpart 13 a of the forward crossbar 13. The forward sliding movement ofthe container 2 ceases when the sloping front wall 2 d of the container2 abuts the correspondingly upwardly sloping part 13 b of the crossbar13. This completes the first step in securing the container 2 to theframe 1, the container 2 becoming engaged with the frame 1 in such asway that the front end of container cannot be lifted from the frame inthe region where bars 14 and 15 fit under the front crossbar 13,although it could still be slid out of said engagement.

In this position, the rearward ends of the longitudinal bars 14 and 15rest on the rearward crossbar 10, and base 2 a just clears (liesforwardly of) the hook 21. At this time, the lever arm 24 will be in adownwards pivoted position due to the action of gravity, and it willoccupy a position in which the tension arm 26 has its base 26 b lyingbelow the hook 21. In the second stage of securing the container to theframe, the end 24 b of the operating lever 24 is gripped and the leveris pivoted in the direction of arrow A towards the rear wall 2 c , itbeing understood that the base 26 b of the tension arm will naturallyengage the hook 21, or will be manually guided into engagement with thehook 21 (FIG. 5) during initial movement of the lever arm 24. The lever24 is progressively pivoted manually as far as it will go (generallyparallel with the rear wall 2 c of the container 2) in order to lock thecontainer in place. This clamps the frame and the container together insuch a way as to prevent the container being slid out of engagement withthe frame at the front end of the wheelbarrow.

During the pivoting of the lever just described, the axis 26 aprogressively moves towards a line passing through the pivot axes 21 aand 25, the tension gradually increasing in the tension arm 26. Then,the lever arm 24 reaches a position in which the axes 26 a, 25, and 21 aare in line with each other, and the tension in the tension arm 26reaches a maximum. After this, the lever 24 snaps to a stable endposition under the force in the tension arm 26. Of course, as thetension in the tension arm increases, the compressive force acting onthe part of the lever arm between the pivot axes 26 a and 25 alsoprogressively increases.

The clamping mechanism 21, 22 just described belongs to a class ofmechanical devices which are sometimes referred to as “over center”mechanisms. Probably the best known use of an “over center” mechanism isin gripping devices known in the United Kingdom as “Mole Grips”, theterm “Mole” being a Trade Mark or Trade name. However, “over center”mechanisms are also commonly used for holding lids closed, for exampleon tool boxes. Similarly, “over center” mechanisms were also used tohold stoppers closed on bottles of carbonated drinks, as were sold underthe trade name Corona.

“Over center” mechanisms can take many forms, but a common feature ofthem is that in their operation, a tensile or compressive force actingon a member progressively increases to a maximum, after which themechanism snaps to a stable position.

When the wheelbarrow is to be collapsed, the assembly process justdescribed is reversed to separate the wheelbarrow into two parts, i.e.the frame and the container. The frame is then folded about hinges 5from its position illustrated in full lines in FIG. 4 to its positionillustrated in dotted line in FIG. 4. This enables the folded frame tobe placed inside the container 2 for stowage and/or transport. Thewheelbarrow when assembled is the same size as conventional availablewheelbarrows, but when collapsed as described above, it can betransported in the boot or other luggage space provided in most privatecars. This enables a worker who is using his own vehicle to travel toand from work to carry a wheelbarrow to and/or from a building site

It will be appreciated that with the wheelbarrow just described,fastening of the container to the frame can be achieved very quicklyindeed, for example, after some experience, in ten seconds. There are nonuts, bolts, or pins which could become lost, damaged, and no tool ofany kind is required. None of the operative parts of the fasteningmechanism lie inside the container 2 to be covered in material such asconcrete carried inside the wheelbarrow.

Many obvious modifications could be made to the wheelbarrow shown in thedrawings. Some examples are given below. Any suitable “over center”locking mechanism could be used in place of the one illustrated. Thepositions of the hook 21 and of the mechanism 22 could be reversed. Thehinges 5 could be replaced by nuts and bolts to enable the two parts ofthe frame to be separated. The wheel 12 could also be readily removable.The two spaced apart longitudinal bars 14 and 15 could be replaced by asingle centrally positioned bar. The container 2 need not becomecompletely detached from the frame in the collapsed condition of thewheelbarrow, since it would be possible for them to remain attached bysome kind of linkage. One could also arrange the lever arm 24 so that itworks similarly to the way described above, but it never actually snapsto an end position. In this case, the locking mechanism would still bean over center type mechanism, but the lever 24 would never reach astable position. In this case, some additional catch would be needed tohold the lever 24 in place against the tension acting to release it.

What is claimed is:
 1. A heavy duty collapsible wheelbarrow comprising:a frame; a container; and a mechanism for securing the container to theframe in an assembled condition of the wheelbarrow, the container beingreleasable from the assembled condition of the wheelbarrow to enable thewheelbarrow to be collapsed, the mechanism for securing the container tothe frame including two connecting members and a locking member, oneconnecting member being secured to a rear wall of the container, theother connecting member being secured to the frame and the lockingmember being movable between a released position and a locking position,the connecting members being engageable with one another to connect thecontainer and the frame together when the locking member is in itsreleased position; and the locking member is movable from its releasedposition towards its locking position with the connecting membersengaged with one another to apply a progressively increasing tensile orcompressive force to the connecting members and prevent the connectingmembers from disengaging in the assembled condition of the wheelbarrow.2. A wheelbarrow according to claim 1, in which the mechanism forsecuring the container to the frame is an over-center mechanism and thetensile or compressive force applied to the connecting membersprogressively increases to a maximum as the locking member is moved fromits released position, after which the locking member snaps to a stablelocking position.
 3. A wheelbarrow according to claim 1,in which theframe has front and rear crossbars which extend transversely of theframe from one side of the frame to the opposite side.
 4. A wheelbarrowaccording to claim 2, in which the frame has front and rear crossbarswhich extend transversely of the frame from one side of the frame to theopposite side.
 5. A wheelbarrow according to claim 4, in which anunderside of the base of the container has means thereon to cooperatewith the front crossbar to prevent the front end of the container frombeing lifted away from the front end of the frame in the assembledcondition of the wheelbarrow.
 6. A wheelbarrow according to claim 5, inwhich the said means on the underside of the container comprise at leastone longitudinal bar.
 7. A wheelbarrow according to claim 6 in which, inthe assembled condition of the wheelbarrow, the forward end of thelongitudinal bar fits beneath the front crossbar to prevent the frontend of the container from being lifted away from the front end of theframe.
 8. A wheelbarrow according to claim 7 in which, in the assembledcondition of the wheelbarrow, the rear end of the longitudinal bar restson top of the rear crossbar.